@article{IM_1976__31_142358,
     author = {Henryk Hecht and Winfried Schmid},
     title = {A {Proof} of {Blattner's} {Conjecture.}},
     journal = {Inventiones mathematicae},
     pages = {129--154},
     publisher = {mathdoc},
     volume = {31},
     year = {1976},
     zbl = {0319.22012},
     url = {http://geodesic.mathdoc.fr/item/IM_1976__31_142358/}
}